Comparison between two different Disability Weights calculations: the case of occupational injuries

Aim: To introduce the concept of DALYs (Disability Adjusted Life Years), in order to calculate the burden of occupational injuries and to compare the disability weights methodology applied by the National Institute for Insurance against Accidents at Work (INAIL) to occupational injuries, with respect to the methodology adopted by the World Health Organization in the Global Burden of Disease Study (GBD), in order to facilitate, on a regional-national basis, the future application of estimates of Burden of Disease due to this phenomenon, based on data available from the NHS. Design: In the first part of the present study, a comparison between the theoretical GBD methodology, based on Disability Weights, and the INAIL methodology based on Gradi di inabilita (Degree of Disability) (GI) described in the table of impairments is made, using data on occupational injuries occurred in Tuscany from 2001 to 2008. Given the different criteria adopted by WHO and INAIL for the classification of injuries sequelae, in the second part, two equations described in the literature have been applied in order to correct systematic biases. Results: In the INAIL dataset, all types of injuries, though often small in scale, have cases with permanent consequences, some of them serious.This contrasts with the assumptions of the WHO, that, apart from the cases of amputation, reduces the possibility of lifelong disabilities to a few very serious categories. In the case of femur and skull fractures, the proportion of lifelong cases is considered by WHO similar to the proportion that in the INAIL dataset is achieved after narrowing the threshold of permanent damage to cases with GI ≥ 33. In the case of amputations and spinal cord injuries, for which the WHO assumes a priori that all cases have lifelong consequences, on the contrary, the greater similarity between the assumptions and the empirically observable reality is obtained after extending the threshold of permanent damage to all cases with even minimal sequelae.The comparison between the WHO DW and INAIL GI, possible only in relation to injuries resulting in permanent damage, shows that in case of injuries of greater severity, INAIL GI are generally lower than the WHO DW. In the case of less serious injuries, INAIL gives instead higher values. The length of temporary disabilities recorded by INAIL is systematically higher than that estimated by WHO. Conclusions: These initial comparisons between the WHO methodology and the cases evaluation performed by INAIL show that the Italian system, based on the gathering of all relevant aspects related to each case, has the potential to utilize and synthesize a greater amount of information. However, wide limits of uncertainty still remain and further empirical findings are needed in order to compare the two systems in terms of precise determination of the DW, the length of disabilities and variations of mortality related to injuries. Language: it